The impact of mass-media campaigns on physical activity: a review of reviews through a policy lens

Abstract Background This review of reviews aimed to: (1) summarize the evidence from published reviews on the effectiveness of mass-media campaigns to promote physical activity (PA) or PA-related determinants (intermediate psychological and proximal outcomes) and (2) to identify policy-relevant recommendations related to successful PA campaigns. Methods An extensive literature search was performed on 1 March 2021. Reviews that evaluated the impact of campaigns on distal (e.g. PA) and/or proximal outcomes of PA (awareness, knowledge, etc.) and that targeted the general population or subsets were included. Quality of reviews was assessed using the AMSTAR-2 tool. Policy-relevant recommendations were systematically derived and synthesized and formulated as good practice statements. A protocol was registered beforehand (ID: CRD42021249184). Results A total of 1915 studies were identified, of which 22 reviews were included. The most consistent evidence was found for the effectiveness of mass-media campaigns on proximal outcomes, while the evidence for distal outcomes was mixed. Good practice statements were derived: (1) to achieve behaviour change, mass-media is an important component of larger, multilevel and multicomponent strategies; (2) mass-media strategies should be coordinated and aligned at local- and national-level and be sustained, monitored and resourced at these levels and (3) media should be tailored to reduce socioeconomic inequalities. Conclusions Mass-media can play an important role in the promotion of PA. In general, evidence was more inconsistent for effectiveness on distal outcomes than for proximal outcomes. Policy-relevant recommendations include that mass-media strategies should be resourced, coordinated, aligned, sustained, monitored and evaluated on the local and national level.


Introduction
S ufficient physical activity (PA) is imperative for public health and the prevention of non-communicable diseases (NCD). However, approximately 25% of adults and 80% of adolescents worldwide do not reach PA guidelines. 1 The World Health Organization has published 'best buys' for tackling NCDs, these include reducing physical inactivity by including community and public education programmes. 2 Increasing population PA levels is a complex challenge that should incorporate multi-facetted interventions targeting several levels of influence. 2 It is suggested that such interventions should target individual-level behaviour, alongside environmental level factors, social norms and policy approaches. The International Society for Physical Activity and Health (ISPAH) has formulated eight investments that work for promoting PA. 1 Mass-media, the core of public education, is one of these investments and aims to raise awareness, transmit consistent and clear messages, and change social norms, to improve population PA 1 The effect of mass-media campaigns to increase PA has been extensively studied over the past decades and summarized in various reviews. [3][4][5][6] Several outcomes related to campaign effectiveness have been evaluated, including campaign awareness, changes in individual psychological determinants related to PA (e.g. intentions, attitudes and knowledge) as well as changes in PA behaviours. 7 The available reviews provide various research angles in their summary of the literature, such as a communication perspective, behavioural theory or an evaluation perspective. Thus far, two umbrella reviews have summarized the evidence, where one mainly focused on mass-media on broader health topics (including PA) 8 and the other focused on PA interventions broader than (but including) mass-media. 9 Thereby, these do not provide a comprehensive overview of the evidence so far. Moreover, of the many reviews published, few reflect on the potential relevance and implications of their results for policy and policy evaluation. Ineffective campaigns can be the result of inefficient policies, since certain barriers and facilitators can be taken into account in policy recommendations to create impactful campaigns. Therefore, viewing the overall effects at different levels, and analyzing which policy recommendations could improve campaign effects, is pivotal. This information is essential to inform and enable policy makers to weigh their choices based on the best available evidence. 10 The role of policy is to change systems and create supportive contexts in which programmes and environments collectively can reduce NCD. Policy interventions provide the framework in which programmes, or in this case media campaigns, are tendered, developed, financed or implemented. 11 Therefore, we aimed (1) to summarize the evidence from published reviews on the effectiveness of mass-media campaigns to promote PA or PA-related determinants (intermediate psychological and proximal outcomes) and (2) to identify policy-relevant recommendations related to successful PA campaigns.
This research is part of the Policy Evaluation Network, a multidisciplinary research network established for the monitoring, benchmarking and evaluation of policies that affect diet, PA and sedentary behaviour with a standardized approach across Europe (www.jpipen.eu). 10 The policy-relevant recommendations derived from this study will be used to inform the development of the PA environment policy index (PA-EPI), a tool for monitoring and benchmarking government progress in implementing public education policies. 10

Data sources and searches
This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement (www.prisma-statement.org) (Online Appendix 5). A comprehensive search was performed on the bibliographic databases PubMed, Embase.com, the Cochrane Library (via Wiley), Cinahl (via Ebsco), SportDiscus (via Ebsco), Scopus and the Web of Science Core Collection, from inception until 1 March 2021. The search was developed in collaboration with a medical librarian (L.S.). Search terms included both controlled terms (MeSH in PubMed and Emtree in Embase) and free text terms. The following terms were used (including synonyms and closely related words) as index terms or free-text words: 'PA', 'policy', 'mass media' and 'impact'. A search filter was applied to limit results to review studies. The search itself was performed without language restrictions, but only manuscripts were eventually included written in English, Dutch and German (see Inclusion criteria further down). Bibliographies of identified articles were hand-searched for relevant publications. Duplicate articles were excluded. The full search strategies for all databases can be found in Online Appendix 1. The protocol and search strategy used were uploaded to PROSPERO prior to carrying out the study (CRD42021249184 11 ).

Study selection
Two reviewers (N.R.d.B. and J.L.) independently screened titles and abstracts of all identified studies. Subsequently, articles selected for full-text screening were retrieved and assessed for eligibility. Inconsistencies were resolved through consensus. Studies were included if they: (1) Studied mass-media campaigns to promote PA. Mass-media was defined as 'Messages (either through text or spoken or pictures or videos) distributed via media intended to reach a mass audience. The most common platforms for mass-media are newspapers, magazines, radio, television, billboards, the Internet and social media' 5 ; (2) studied change in PA behaviour (direct) or changes in intermediate outcomes including awareness, attitude, beliefs, social norms, intention and knowledge in relation to PA (indirect); (3) presented a summary of evaluation studies, either as systematic review, meta-analysis or narrative review; (4) studied the general population or subsets (such as socio-economic groups and children) and (5) written in English, Dutch or German. Studies were excluded if interventions targeted clinical populations (i.e. specific patient groups).

Data extraction
Two reviewers (N.R.d.B. and J.L.) performed data extraction according to a standardized protocol. Extracted information included (1) data on review study: aim, in-and exclusion criteria, design, databases, observed results, policy implications and (2) data on primary studies: included campaigns, country, effect, policy level, target population, combined actions and duration. A random subset of extractions (n ¼ 5) was cross-checked by the other reviewer (N.R.d.B. and J.L., as appropriate) for quality assurance.

Risk of bias
Four independent reviewers (N.R.d.B., J.L., S.M. and E.G.B.) performed a risk of bias assessment using the AMSTAR-2 tool for systematic reviews. 13 Studies were rated as 'high confidence' if no more than one non-critical weakness was identified, as 'moderate' with >1 non-critical weaknesses, as 'low' when one critical weakness was identified (with or without non-critical weaknesses) and as 'critically low' when >1 critical weaknesses were identified (with or without non-critical weaknesses). 13 Details of this tool were described elsewhere. 13 Since AMSTAR is designed to assess risk of bias in systematic reviews, narrative reviews received a lower score by definition.

Data synthesis
We systematically described core characteristics of each review, including the review design, whether the review evaluated PA campaigns only (or a broader range of mass-media campaigns), review aim, overall results, policy implications for evaluation, monitoring and benchmarking and the risk of bias score. We systematically extracted data from each of the included media campaigns and described effectiveness, policy level, country, target population and how often the campaign was identified in the included reviews referred to as overlap in primary studies between reviews. The results were structured according to the levels of outcome based on the analytic framework by Brown et al. 7 (figure 1). The framework distinguishes the effects of mass-media at various levels: the proximal level (i.e. awareness of messages), intermediate level (i.e. changes in knowledge, intentions and attitudes) and distal outcomes (i.e. changes in PA), which leads to better health outcomes (reduced morbidity and mortality). Also, we classified each campaign according to a typology inspired by Gelius et al., which was initially developed to differentiate policy documents. 14 We categorized campaigns according to their policy level and their level of impact (see detailed structure in Online Appendix 2). Based on this typology, we differentiated between national and subnational campaigns (policy level) and used the framework by Brown et al. ( figure 1) as a guidance for describing the level of impact generated by the study. Overlap of primary studies between reviews was assessed according to methods by Pieper et al. 15 This was done for overlap of primary studies (publications) as well as at the level of campaigns. The overlap was presented as the corrected covered area (CCA).

Search results
Out of the 1915 identified references, 50 full articles were retrieved and further assessed, with 22 included in our study (figure 2). Fourteen studies received a critically low-quality rating in the risk of bias assessment, 6,7,9,[16][17][18][19][20][21][22][23][24][25][26] three received a low-quality rating, 3,27,28 two received a moderate quality rating 29,30 and three received a highquality rating 8,31,32 (Online Appendix 3). There was a study overlap of 6.8% of campaigns between reviews, with the most cited campaign being Wheeling Walks (covered in 10 reviews) followed by Active Australia (in 8 reviews), Active for life (in 7 reviews) and VERB (in six reviews) (Online Appendix 4).   Table 1 summarizes the characteristics, results, policy implications and risk of bias of the included reviews. Results are discussed below, structured by outcome level.

Mass-media campaigns and proximal outcomes
Eleven out of 22 reviews reported specifically on awareness and recall as proximal outcomes of PA mass-media campaigns. The earliest review dates from 1998 and reports high campaign recall. 6 Updates of this review in 2004 and 2005, as well as other reviews, both confirmed that campaigns increased awareness. 7,8,18,20,21,23,26,27 Awareness was raised as an important target, since this is the most proximal endpoint and may act as an important step towards effectiveness of campaigns on behavioural outcomes. 32 Authors of reviews that focused on proximal endpoints argued that effectiveness on more distal outcomes might be harder to detect and more proximal endpoints may therefore be suitable to support policy changes and agenda setting. 32

Mass-media campaigns and intermediate outcomes
Seven of 22 reviews reported on outcomes related to changes in knowledge, intentions and attitudes. One review concluded that relatively few primary studies included such intermediate outcomes (6/ 16), 7 while a more recent review indicated that such outcomes were more commonly evaluated (16/23). 28 The reviews showed modest, but usually positive changes in intermediate outcomes, following mass-media campaigns, 7,8,18,23,26,28 see also

Mass-media campaigns and distal outcomes
All included reviews reported on behavioural outcomes. Reviews that were conducted longer ago (1998)(1999)(2000)(2001)(2002)(2003)(2004) highlighted that the lack of studies on PA outcomes was an important research gap and that if it was studied mostly inconsistent or limited impact on PA outcomes was observed. 6,20,32 Six recent reviews (2005-2019) reported positive behavioural outcomes following mass-media campaigns and/or reported promising outcomes when combined with other initiatives. 3,8,17,19,21,28 Campaigns that focused on social norms (rather than risk messaging) were found to be most effective, as were those targeting specific PA behaviours (such as walking). 3,17,27 The campaign most frequently cited was VERB, the successful elements of which were audience segmentation, multiple media use and embedding in existing community programmes (multi-component interventions). Although stand-alone PA media campaigns were found to have insufficient evidence of effectiveness in one review, 7 another review concluded in more general terms that conducting any kind of campaign was more beneficial than not conducting one, regardless of the theory, methods or channels used. 17 However, a post hoc analysis of studies included in the review of stand-alone mass media campaigns 7 also found that the more successful campaigns included formative research, audience segmentation, message design, channel placement, process evaluation and theory-based frameworks as part of their campaign design and planning. 33 About half of the reviews concluded that there was inconsistent evidence with regard to PA improvements following mass-media campaigns. There were some key explanations identified for these inconsistencies. First, some reviews observed that effects were mainly found in motivated (selective) subgroups or in those with significant effects on proximal and intermediate outcomes. 16,27,34 Second, reaching vulnerable subgroups of the population was reported to be a challenge and the extent to which campaigns can be used to address inequalities (e.g. targeting subgroups in tailored ways) should be further explored. 6,7,17 Third, interventions that were combined with other initiatives 16,19,23,24,29 seemed to be more promising and effective than stand-alone campaigns. 7 However, a recent review found only few examples of integrating mass-media into broader prevention strategies. 26 Fourth, a solid evaluation of population-scale approaches is challenging and there is a lack of consistency in the quality of evaluation methods used across studies of mass media campaigns. Moreover, many studies used self-reported PA measures without commenting on the validity and reliability of these measures. 7 A solid evaluation and use of monitoring frameworks to evaluate campaigns over a longer term was lacking in many studies, hampering the quality of these studies, potentially preventing them from observing effects. 7,8,18,19,22,23,26,27 Longer-term studies that evaluate campaign interventions would also enable investigators to gain a deeper understanding, and better inform policy-makers, about the extent to which changes in PA behaviours resulting from massmedia campaigns are sustainable.

Policy recommendations
When assessing the reviews through a policy lens, three main topics were identified to inform policy evaluation, monitoring and benchmarking.
First, reviews argued the need for strategies to support long-term and sustained initiatives/strategic plans. 6,18,19,22 An important mechanism reported to change behaviour with media campaigns is through changing social norms, and because social norms do not change overnight, support for long-term strategies is essential. 18 A key challenge to sustained and long-term strategies is, however, that funding is often on the short term and allocated too narrowly. 18 Sustained government and community support, in addition to funding, is a requirement that was also reported in multiple reviews, 18,19 as well as integration of mass-media in long-term strategic plans of state and local public health agencies. 19 State and local agencies should incorporate standardized and routine evaluation and monitoring, according to theoretical frameworks, 6,9,19,22,23,27 which in turn should lead to more solid evidence for the use of mass-media campaigns. In addition to evaluate effectiveness, it would also be valuable to perform economic analysis of costs and benefits. As costeffectiveness data are often lacking, incorporating it in sustained and systematic monitoring and evaluation schemes would be beneficial. 8 Finally, evaluation frameworks are generally short-term and narrow (focused on individual behaviours) and therefore often too limited to assess broader impacts that media campaigns may have beyond the individual, also as part of larger combined community interventions.
The second cluster of policy recommendations that was observed across systematic reviews was that mass-media outings should be incorporated in larger combined community interventions and broader prevention strategies to reach the highest impact. 6,7,16,[18][19][20]22,26,28,32 Mass-media campaigns help to change awareness, knowledge, attitudes and social norms, laying the foundation for subsequent behaviour change through combined interventions. 7,18 Partnerships across multiple levels and organizations/agencies can work well to implement PA campaigns in services and events that stimulate the desired PA behaviours and to enable coordinated, collaborative and sustained efforts. 6,9,20,21 Also, such collaborations are warranted to create coherent and consistent messaging. 9,19 Links to existing organizations could work well locally. 6 Moreover, local partnerships can help to target messages better to local culture and region. 9 However, despite the recognized need for mass-media to form part of a broader approach, recent reviews indicated that integration into broader strategies was rare and that policy and/or environmental dimensions were not often integrated with media campaigns. 7,8,26 The third policy implication concerned audience segmentation. Mass-media messages are inherently designed to reach a mass audience. However, reviews criticize that this is not the most effective approach and that messaging should be tailored, by applying audience segmentation. 6,7,9,16,17,21,31 Multiple reviews indicated that media messages should be evidence-based. 22 But the evidence for ethnic minority subgroups is still thin. A few reviews aimed iv74 European Journal of Public Health selected media channels, small media in residential areas, outreach packets through community networks and/or content conveyed by people from target groups. Also, the content was adapted to culture; selected cultural expressions were tested in target group and/or addressed unique cultural barriers -The available evidence is inadequate for understanding whether mass-media inter-  iv80 European Journal of Public Health specifically to assess the equity impact of mass-media interventions. 25,31 One of these observed that when campaigns focused specifically on low socioeconomic subgroups, they were generally more effective in reaching this group, 31 while the reach of broadly targeted was equal in high and low socioeconomic groups. 6,25 Outcomes of broad campaigns were not large enough to reduce socioeconomic inequalities. More appealing and targeted approaches are needed to maximize effectiveness in strata of the population and evaluating those effects well. As the evidence so far for effectiveness of tailored interventions is thin, this warrants further investigation and evaluation. 25,31 Discussion This review of reviews compiled the evidence on effectiveness of mass-media campaigns to promote PA or PA-related determinants (intermediate psychological and proximal outcomes) and derived relevant recommendations for policy. The current evidence acknowledges that there are various levels of impact of massmedia campaigns and that campaigns can have a pivotal role in changing social norms and awareness. In general, the more distal the outcomes under study, the smaller and more inconsistent the evidence base for effectiveness. As a result, the current evidence for mass-media campaigns indicates that the effectiveness on PA behaviour is limited. Some policy-relevant characteristics related to successful PA campaigns were identified: (1) to achieve behaviour change, mass-media campaigns are important as a component of larger, multilevel and multicomponent interventions/strategies; (2) mass-media strategies should be coordinated and aligned on the local and national level and should be sustained, monitored, evaluated and resourced at these levels and (3) media should be targeted and tailored to specific population sub-groups in order to better address socioeconomic inequalities. The evidence observed in the current review of reviews was in line with two earlier umbrella reviews. 8,9 Stead et al. also indicated impact of campaigns on knowledge and awareness, but mixed results on behavioural effectiveness (smoking, sexual health and PA). Heath et al. acknowledged the effectiveness of mass-media campaigns to change behaviour mainly when linked to specific community campaigns. 9 These conclusions also align with proposed theories on the working mechanisms of mass-media campaigns. Wakefield et al. suggest that campaigns can affect PA behaviour either directly or indirectly, for example through agenda setting, social norms and public policy. 35 Also, the framework by Brown et al. focuses narrowly on PA behaviour and assumes that a linear impact of awareness on increased knowledge, intentions, attitudes, beliefs, behaviour change and better health outcomes are needed, if mass-media campaigns are to be effective. However, not all the links in the pathway are that well established. For example, the association between health behaviours and better health outcomes is well established; however, this applies less to the association between behavioural determinants (awareness, knowledge, etc.) and health behaviours. The well-known intention-behaviour gap 36 indicates that there may be many barriers or facilitators to the translation of such determinants into behaviour. Socio-ecological models suggest that effective policies and supportive environments are among those facilitators. 37 As indicated in the 'people and places framework' 38 and the Global Action Plan on PA (GAPPA), 39 interventions should not solely focus on individual behaviour change (downstream), but should be part of a larger strategy where physical, socio-cultural, political and economic systems (upstream) work together. Effective policies are thus imperative to the successful use of mass-media campaigns.
From the policy lens that this review took, several good practice statements for mass-media policies were derived. A challenge is that campaign implementation is dependent on political or health agency decision-making 29 ; therefore, a tool like the PA-EPI can be important to hold political decision-making accountable. The first and second good practice statements for inclusion in this tool illustrate that coordination of national/subnational strategies as well as public private partnerships, and a focus on long-term monitoring and resourcing at these levels, will enhance evaluation, monitoring and benchmarking of mass-media campaigns. Monitoring will be important to evaluate and recognize successes and failures of mass-media strategies and to assess (a) the reach among specific subgroups, (b) the impact of massmedia campaigns on the long-term and various outcomes and (c) the health impacts of sustained and coordinated initiatives. This requires policies to be developed with a longer-term focus and monitoring and surveillance systems that capture indicators of effectiveness and reach. Also, monitoring and sustained efforts will play a crucial role in determining cost-effectiveness of mass-media campaigns and combined efforts and play a role in supporting long-term strategy plans 8,16,19 .
Cost-effectiveness studies were outside the scope of the present review, but one previous umbrella review assessed cost-effectiveness of PA interventions (including mass-media). 40 This review supported the costeffectiveness of mass-media, but also acknowledged the debate of overall effectiveness to change behaviour through mass-media alone. However, the WHO has identified public education and awareness campaigns (incl. mass-media campaigns) combined with other community-based education, motivational and environmental programmes, to be a 'best buy' for reducing physical inactivity. 2 This supports the need for collaboration at the local and national level as well as public private partnerships, and sustained actions to make these initiatives impactful, as outlined in our second good practice statement. It should also be noted that we did not perform exclusions of reviews based on funding of included interventions, while privately funded interventions may have competing interests as opposed to public funded interventions. We did choose to include reviews that selected both types of interventions, to be able to include a perspective on partnerships on multiple levels. We conclude that public-private partnerships can work well when collaboration and interests of programmes are well aligned. Nevertheless, we included the funding sources per intervention in Online Appendix 4, to be transparent on funding sources of each included intervention. Also, focus on upstream determinants of PA and outcomes of mass-media campaigns, and incorporating this in monitoring frameworks, will provide a more holistic view of the effects reached by combined efforts and mass-media, as highlighted by good practice statement 1. Thirdly, tailoring of mass-media to specific population sub-groups emerged as good practice in the present review. Groups with a low socio-economic status are difficult to reach and these are the groups with highest potential gains to be made in terms of health impact. In many of the included reviews, this tailoring was raised as an important research gap and the existing evidence base is thin. While mass-media campaigns in themselves will likely not bridge and eliminate the socio-economic disparities in health, tailoring existing initiatives can increase access to health-enhancing activities and initiatives for lower socio-economic groups. This review of reviews should be interpreted in light of some limitations and strengths. First, it included only published reviews but not grey literature and by design, the most recent primary studies have not been included. Also, the quality of the evidence in a review depends on the quality of the included studies. We saw that, in general, older reviews scored lower in terms of quality, which is not surprising given that standardization of literature searching, appraisal and reporting has only become common practice over the last decade. Moreover, review studies did not always adequately specify whether proximal determinants referred to the awareness of the campaign or the health issue (i.e. determinant(s) of PA behaviour or PA behaviour); therefore, we could not provide these details in the present review. One additional limitation is that current reviews often recommend that mass-media campaigns should be included as one component of larger, multilevel and multicomponent interventions/ strategies. However, policy-makers may want to know what additional components should be added to a mass media multicomponent campaign and/or what is the impact each individual component may contribute to behaviour change. The research literature does not provide direct answers to this question. It may make good common sense, though, for policy-makers to engage community members or the intended audience of the mass-media campaign, to help tailor the additional components of the multicomponent intervention, based on their needs and preferences. This may be especially important when planning and implementing interventions to address health and economic disparities.
Despite these limitations, the review provides a comprehensive overview of the state of the art in the field of mass-media for PA promotion, as well as important and concrete entry points for policy regarding the enhancement of PA through mass-media. The evidence showed that mass-media can play an important role in the promotion of PA, as it can clearly impact on important determinants of PA and might contribute to enhancing PA behaviours-although the latter may only be expected when media outings take place alongside additional PA promotion approaches.